1. Field of the Invention
The present invention relates to an Internet phone protocol, and more particularly, to an Internet phone protocol by which one Internet phone can be independently linked to all of the other Internet phones connected to a LAN by transferring its own status information without a call server.
2. Description of the Background Art
Recently, in a business office environment, a LAN (local area network) is becoming an important communication resource more than an interphone network. In this respect, however, the LAN and the interphone are separately networked, which causes double expense incurred for maintenance.
In an attempt to solve the problem, the interphone network has been substituted with the LAN by a terminal (referred to as Internet phone, hereinafter) which is operable in the LAN.
FIG. 1 shows a LAN construction where a protocol based on the call server is applied to an Internet phone in a conventional art. As shown in this drawing, a plurality of Internet phones (IP Phone 1-IP Phone N) and a plurality of personal computers (PC1-PC N) are connected to the LAN. A call server having all the status information of the Internet phone and relay linking between Internet phones is also connected thereto.
Linking process of the conventional Internet phone as constructed above will now be described with reference to accompanying drawings.
FIG. 2 is a state view of the linking process of the Internet phone in accordance with the conventional art. As shown in this drawing, a call process for linking is started as a first Internet phone (IP Phone 1) starts to output a setup message to the call server.
The call server checks a status of the first Internet phone (IP Phone 1) and a second Internet phone (IP Phone 2) desired to be linked by the first Internet phone, to judge whether or not they can be linked. Upon such judgement, if the second Internet phone is in a feasible status for linking, the call server outputs a setup message to the second Internet phone.
Upon receipt of the setup message, the second Internet phone confirms whether or not itself is in a feasible status for linking, and outputs a connection message to the call server, and then, the call server outputs the connection message to the first Internet phone, thereby linking the first and second Internet phones.
However, operated according to the protocol based on the call server, the conventional Internet phone does not have any other information than its own status information. And, since the call server has the status information of all the Internet phones connected to the LAN and relays linking between the Internet phones, if the call server is malfunctioned, communication itself between the Internet phones is impossible. Moreover, since the call server is needed even for operating only one or two Internet phones, it is very inconvenient for users to easily access for use.
Therefore, an object of the present invention is to provide a status message structure for Internet phone in which one Internet phone independently transfers its status information to all of the other Internet phones connected to a LAN so that it can be directly linked to a desired Internet phone without a call server, thereby building up an interphone network by merely connecting the Internet phone to the LAN.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided an Internet phone protocol including: a physical hierarchy for providing a mechanic and functional units for connecting, maintaining and releasing between linking media; a device driver hierarchy for defining driving characteristics of each electric and mechanic unit of the physical hierarchy; a real time operating system (RTOS) programming hierarchy for controlling an overall system; a user datagram protocol (UDP)/Internet protocol (IP) hierarchy for defining characteristics for processing a packet stream in packet change; an interface hierarchy for receiving a user""s intention to a system; a voice/real-time transport protocol (VOICE/RTP) hierarchy for linking a voice channel between Internet phones; and an independent multimedia office communication system protocol (referred to as MOCS protocol hereinafter) hierarchy for rendering Internet phones to store in exchange status information to each other for independent and direct linking.